Presently, group III-Nitride-based transistors such as gallium nitride (GaN)-based high electron mobility transistors (HEMTs) are typically Depletion-mode (D-mode) devices, which use a negative gate voltage with respect to source voltage in order to pinch-off current flow in the transistor channel. However, Enhancement-mode (E-mode) devices, which use a positive gate voltage with respect to source voltage in order to pinch-off current flow, may be desirable for applications such as power switching. E-mode devices can be fabricated by controlling a thickness of a supply layer to be less than a critical thickness such that a two-dimensional electron gas (2DEG) does not form in the channel beneath the gate during operation of the transistor. However, conventional recess and deposition processes to form the E-mode device may induce traps or other defects at an interface of the gate and channel.